1. Field of the Invention
The invention is directed to an improved fuel injection system for an internal combustion engine.
2. Description of the Prior Art
One known fuel injection system known from the literature, such as Dieselmotor-Management [Diesel Engine Management], published by Verlag Vieweg, 2nd Ed. 1998, pages 280 to 284 has a high-pressure side, which includes a high-pressure reservoir and injectors communicating with it for fuel injection at a cylinder of the engine. The high-pressure side furthermore includes a high-pressure pump, by which fuel is pumped into the high-pressure reservoir. The fuel injection system also has a low-pressure side, which communicates at least indirectly with a fuel tank. The low-pressure side may be the fuel tank, a return to the fuel tank, or a supply communication by way of which the intake side of the high-pressure pump is supplied with fuel from the fuel tank. A low-pressure pump, by which fuel from the fuel tank is delivered to the intake side of the high-pressure pump, may be disposed in the supply communication. The high-pressure side is separate from the low-pressure side, to avoid fuel leakage. During engine operation, the fuel warms up, especially in the high-pressure side of the fuel injection system. If the engine is shut down after a relatively long period of operation, the fuel in the high-pressure side cools down, thus decreasing in volume, which can lead to the formation of vapor bubbles in the high-pressure side. As a result, the later re-starting of the engine is more difficult, because first the vapor bubbles in the high-pressure side must be positively displaced, before a fuel injection and hence combustion in the engine can begin.